Swim strokes in jellyfish and Medusoid. In both systems, the power stroke accelerates the fluid and generates thrust (right, top). This could also be used for pumping fluid. The recovery stroke generates a vortex that draws fluid towards the bell (right, bottom). This vortex helps jellyfish capture their prey. In the engineered system, the current could feed fluid-surface reactions. Credit: Image courtesy of Janna Nawroth